The communications industry shows a growing interest in using wireless communication technology to transmit data to and from remotely located devices, equipment, or machines. A cellular mobile radiotelephone (“CMR”) system or network can transmit data between a user and a remote device such as a vehicle, vending machine, utility meter, security alarm system, community antenna television (“CATV”) pay-per-view (“PPV”) terminal, etc. The user can obtain telemetry data from sensors or other data acquisition apparatus coupled to the device to remotely acquire information about the device's operations, operating status, or operating environment. The user can also send messages to the device via the CMR system, for exampling requesting specific information or controlling some aspect of the device's operation.
As an alternative to consuming the voice-carrying bandwidth of the CMR system, two-way communications between remote equipment and a central facility or other site can transmit on the CMR system's secondary channels or overhead control channels. That is, the control channels of a CMR system, such as an advanced mobile phone system (“AMPS”) cellular system, can support data communications with devices with minimal impact on person-to-person voice communications. In its role for voice communications, an overhead control channel transmits data that controls communication actions of mobile and portable radiotelephones operating on the CMR system. An overhead control channel, which typically supports digital communication, can be a paging channel or an access channel, for example. The cellular system uses the control channels to communicate information for handling incoming and outgoing call initiations between the cellular system and a cellular customer. Since these control channels generally have greater message handling capability than the cellular system needs for handling voice traffic, they can convey telemetry data without impairing voice communications.
In this manner, bidirectional data communication with a telemetry system, such as a monitor, controller, sensor, or similar device coupled to a data source, proceeds on the overhead control channel. Such a telemetry system may comprise a CMR transceiver that sends and receives data on the overhead control channel. The term “telemetry system,” as used herein, refers to a system that acquires, senses, or otherwise obtains information from a remote machine, apparatus, device, or other source and transmits the information to a receiving station or site for recording, analysis, viewing, or other purpose. An individual or a computer can request and obtain position, movement, or geographic data from a telemetry system attached to a vehicle by communicating on the overhead control channels of the CMR system, for example. To name a few more of the numerous potential applications, the overhead control channels can convey messages that comprise security alarm reports, copy counts for photocopiers, utility meter readings, pipeline corrosion monitoring results, vending machine sales, railroad crossing gate information, pollution data, geo-positions of containers, and control signals for electricity, solenoids, or fluid flow.
The communication of telemetry data and device commands to and from a CMR transceiver of a telemetry system can overlay upon the control channel infrastructure that the CMR system uses for handling roaming cellular telephones. Such telemetry communication over an overhead control channel can emulate or mimic a CMR system's verification of a cellular telephone operating outside of its home system, known as roaming. Upon power up, a roaming cellular telephone recognizes that it is outside its home system and sends its Mobile Identification Number (“MIN”) and Electronic Serial Number (“ESN”) to the cellular system over an overhead control channel. The cellular system recognizes the roaming number and routes the MIN and ESN to the roaming cellular telephone's home system for validation via an inter-cellular network, known as the intersystem signaling or Electronic Industries Association/Telecommunications Industry Association (“EIA/TIA”) Interim Standard 41 (“IS-41”) network, that interlinks multiple cellular systems throughout the United States and uses signaling system 7 (“SS7”) protocol.
The assigned MIN address of each transceiver causes the CMR system to route transmissions having that MIN address (and accompanying ESN digits) to a communication gateway that handles telemetry communications via the IS-41 network. While the MIN identifies the transceiver/telemetry system, the ESN data field carries telemetry data, for example in the form of a 32-bit message. The communication gateway adds a timestamp to each communication that it handles. The IS-41 network adds a coarse location of the message's point of origin, known as a mobile switching center identification (“MSCID”).
A typical AMPS cellular telephone system may have 42 overhead control channels that are assigned among competing cellular carriers in each market. Each overhead control channel has a forward overhead control channel (“FOCC”) and a reverse overhead control channel (“RECC”). The FOCC conveys information from the cellular base station to the cellular telephone. Conversely, the RECC conveys information from the cellular telephone to the base station. The cellular system initiates each cellular telephone call using the overhead control channels and then directs the cellular telephone(s) associated with the call to a voice channel. Upon establishing the service on a voice channel, the overhead control channel clears, thereby becoming free or available.
The FOCC broadcasts information concerning the system identification (“SID”) of the cellular system on a frequent basis for receipt by cellular telephones in the broadcast domain. When a cellular telephone powers up or is turned on, it compares the SID of its home system, which it stores in non-volatile memory, to the broadcast SID. If the comparison indicates that the cellular telephone is roaming, the cellular telephone checks the FOCC message stream for registration instructions from the local cellular system operator. The instructions may command each roaming cellular telephone to register its identity over the RECC to the cellular system on a time basis, such as daily, or an event basis at each call.
When the roaming cellular telephone registers with the non-home or roaming cellular system, it sends its MIN and ESN via the RECC to the mobile switching center (“MSC”). The IS-41 provides connectivity between each of the MSCs in the United States and facilitates identifying roamers.
For example, suppose a cellular user having a home base in Miami is roaming in an Atlanta cellular system. Recognizing that the first six digits of the roaming cellular telephone's MIN do not correspond to an Atlanta cellular telephone number, the Atlanta MSC determines that the cellular telephone is not one of its Atlanta cellular customers. The Atlanta MSC compares the first six MIN digits to a database and determines that the cellular telephone's home MSC is Miami-based. Once identified, the Atlanta MSC routes a request for validation to the cellular telephone's home MSC in Miami. In response to the request, the home MSC in Miami checks its local database to validate the MIN and ESN, determine if the customer's bill is current, and identify any custom calling features that the customer is entitled to receive. The Miami MSC sends a registration notification or validation response comprising the requested information back to the Atlanta MSC. Through this process, the validated roaming cellular telephone customer receives the same level of cellular service in the Atlanta MSC as in the home MSC in Miami. Meanwhile, the Atlanta MSC receives assurance that the roaming cellular telephone customer is not fraudulent.
Messages containing telemetry data have the same outward format as the validation messages of the Miami-to-Atlanta roaming example. Thus, the CMR system's roaming registration process handles each telemetry message as if it was an actual validation message from a roaming cellular telephone. However, rather than directing the telemetry messages to an MSC of a cellular service provider, the communication gateway captures or intercepts telemetry messages on the RECC to obtain the telemetry data carried thereon. Information added to the database of the roaming MSC controls the dedicated MINs that are assigned to the communication gateway. The CMR transceiver, comprising a telemetry radio, emulates the roaming cellular telephone. In a telemetry scenario, the MIN is the 10 digit equipment identification (“ID”) and the ESN comprises the data payload.
In order to appear transparent to the cellular system, the communication gateway emulates a home MSC. The communication gateway sends the proper validation response, indicating that the MIN and the ESN are valid, back to the roaming MSC. After a preset period of time, the communication gateway sends a registration-cancel message for each telemetry message. This action avoids filling up the visitor location register (“VLR”) of the roaming MSC with unnecessary entries. That is, deleting the VLR entries prevents the registration from remaining in the roaming MSC's VLR for an extended period of time. In contrast, standard registrations associated with voice traffic remain in the VLR until a specified time for re-registration occurs, which could be as long as 24 hours, or until the home MSC informs the roaming MSC that the roaming cellular telephone has moved to another MSC system.
For communication to the telemetry system via the FOCC, the communication gateway accepts outgoing messages via an Internet protocol (“IP”) message transmitted on frame relay, Internet, or a landline phone call. The communication gateway, in turn, sends a message to the visiting MSC via the SS7/IS-41 network. The MSC's translations database has a configuration that accepts the MINs associated with telemetry communication in the MSC's market area.
Since an outbound or forward message does not have an ESN field, an alternate coding system provides remote control of the telemetry transceiver and its host equipment. In one conventional technique, aggregating multiple outbound messages creates a small data packet. That is, a plurality of outbound messages, transmitted serially on a singe FOCC, each carry a portion of a command or instruction. The telemetry transceiver receives the serially transmitted messages, each containing a message fragment, and merges these fragments into a unified message. This technique is often inefficient and limited in terms of its speed of message delivery.
In another conventional technique for communicating messages to a telemetry system, each potential message has a corresponding unique MIN. The telemetry system recognizes receipt of the unique MIN as delivery of a specific instruction. For example, a vending machine operator may send out a specific MIN on an FOCC to request sales data from a vending machine having a telemetry system. In this conventional technique, each unique MIN corresponds to exactly one identifiable message. The number of messaging MINs assigned to each telemetry system has a one-to-one correspondence to the number of messages that the telemetry system can interpret. CMR systems typically do not have an unlimited number of MINs, and assignment of each MIN incurs an associated cost. Thus, one disadvantage of this technique is its consumption of MINs.
Another conventional scheme for communicating with a telemetry system uses a single overhead control channel for bidirectional communication. The telemetry system receives an instruction on the FOCC of an overhead control channel and returns a response to the instruction on the RECC of the same overhead control channel. One problem with this scheme is that the RECC typically does not become immediately available for sending a reply following transmission of the instruction on the FOCC. Depending on the speed of the MSC, a CMR system may need up to 65 seconds to clear the overhead control channel prior to communicating the reply on the RECC. Because the MSC and the CMR system perform multiple steps to provide forward and reverse communication, the aggregate time for sending an instruction message to a telemetry system and receiving a response message from the telemetry system can be two times 65 seconds, or 130 seconds. During this delay time, the MSC builds a VLR entry and then deletes or “tears down” the entry in response to instructions from the communication gateway. As discussed above, deleting VLR entries associated with telemetry messages preserves the available capacity of the VLR database. One shortcoming of this conventional scheme is that the communication latency or time delay can pose problems for telemetry applications. For example, the 130-second delay can be unacceptable in certain time-critical circumstances.
An application of wireless telemetry that often has little tolerance for such delays is remote monitoring or control of a vehicle. If a vehicle owner needs to find his or her vehicle, the owner may lack the patience or the time to wait 130 seconds or some other significant period of time to receive the vehicle's location over a conventional overhead control channel.
Power consumption or battery life often poses another problem for many conventional telemetry systems mounted in vehicles for mobile operations. That is, telemetry devices based on conventional technology may not offer a sufficient level of energy efficiency. If all of the subsystems associated with the telemetry system are powered up and operational and the vehicle's alternator is not recharging the vehicle's battery, the total power consumption may pose an unacceptable battery drain. On the other hand, if all of the vehicle's telemetry capabilities are turned off or disconnected from the battery, all telemetry functionality may be lost. Conventional telemetry systems often fail to operate in a manner that adequately preserves battery life while providing an acceptable level of functionality or readiness. For example, a car dealer may want all of the telemetry system's capabilities to remain immediately available for on-the-spot demonstrations to potential customers. However, to maintain the desired level of readiness, a conventional telemetry system may drain the vehicle's battery in an unacceptably short period of time.
Another problem with some conventional telemetry systems that monitor vehicles is that they may fail to provide a sufficient level of functional capability. Such a telemetry system may monitor a vehicle's operation and provide notification to a remote owner upon an occurrence of a designated event, such as a theft attempt. However, the telemetry system may fail to consider the circumstances surrounding the event or other events that preceded or followed that event. In other words, conventional technology for vehicle telemetry may not provide an adequate level of processing or analysis of sensor data. Without adequate processing of sensor data, a user of the telemetry system may be overwhelmed with extraneous data or false alarms. The data of interest to the user may be buried in the extraneous data and not readily apparent. Thus, telemetry systems based on conventional technology may not adequately highlight operating conditions or events of potential concern to the vehicle's owner.
To address these representative deficiencies in the art, what is needed is an improved capability for monitoring and controlling a vehicle via wireless telemetry. A further need exists for a capability for providing telemetry functionality on an as-needed basis while managing power consumption. Yet another need exists for processing telemetry data to identify conditions or events that warrant sending a notification or alert to a remote party.